# NeuroPhIBER: A Nimble Fiber-Optically Read Silicon Microelectrode Array

> **NIH NIH R21** · JOHNS HOPKINS UNIVERSITY · 2020 · $476,494

## Abstract

Project Summary/ Abstract
Advancements in microelectrode array (MEA) neural probes have allowed the number of neurons that can be
simultaneously recorded by implantable electrodes to roughly double every 7 years since the 1970s, with present
state of the art devices allowing for simultaneous recording from thousands of neurons. Unfortunately, continued
growth in MEA recording performance faces tremendous challenges from the interrelated constraints on
invasiveness of implantation (i.e. probe size) combined with the need for higher capacity and density electronic
voltage recording and data read-out circuitry. Specifically, the impedance and resulting noise of conventional
electrodes increase dramatically as electrode size is reduced. Furthermore, higher density electrode read-out
requires a large number of parallel electrical traces with high impedance and capacitive crosstalk. This has led
to the need for relatively large size, weight, and power multiplexing circuitry integrated into the base and even
the shank of the probe, which is both physically cumbersome and can cause significant tissue heating from
power dissipation. The focus of this proposal is to develop a scalable, passively wavelength multiplexed,
ultrahigh-bandwidth silicon photonic probe architecture that is capable of relaying optically-encoded voltage
information from thousands of electrode sensing sites through an ultrathin, lightweight, and flexible optical fiber.
We term this approach NeuroPhIBER (NeuroPhotonic Interface for Bio-Electronic Recording). Notably, the
proposed architecture leverages existing mature fiber optic telecommunications and CMOS-compatible silicon
photonic technologies to create a fully passive probe where all active signal processing is performed remotely.
First (Aim 1), we will develop the NeuroPhIBER MEA sensing site unit cell. This will involve creating a silicon
photonic modulator with Q ~ 25,000 to serve as a sensitive voltage sensor for converting our extracellular neural
voltage signals to an optical signal that is subsequently coupled to an optical fiber and remoted to the
detection/signal processing station. Second (Aim 2), we will multiplex the unit cell within the NeuroPhIBER MEA
probe up to a goal of 32 passively wavelength multiplexed devices onto a single bus waveguide. This will enable
us to record from 100s of sensing sites using multiple spatially multiplexed bus waveguides on a single probe
shank, enabling high spatio-temporal resolution neurological recording. Lastly (Aim 3), we will perform an in vitro
validation of our NeuroPhIBER MEA probe using primary murine cortical cultures. This will enable us to
quantitatively study individual neurons and function in a controlled environment.

## Key facts

- **NIH application ID:** 10047889
- **Project number:** 1R21EY031854-01
- **Recipient organization:** JOHNS HOPKINS UNIVERSITY
- **Principal Investigator:** Amy Carole Foster
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $476,494
- **Award type:** 1
- **Project period:** 2020-09-01 → 2023-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10047889

## Citation

> US National Institutes of Health, RePORTER application 10047889, NeuroPhIBER: A Nimble Fiber-Optically Read Silicon Microelectrode Array (1R21EY031854-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10047889. Licensed CC0.

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